By default iptables firewall stores its configuration at /etc/sysconfig/iptables file. Type the following command to see its

# cat /etc/sysconfig/iptables

Or

# iptables -L

Temporarily delete all the firewall rules

At first, create flush.iptables script with following command

# vi flush.iptables

Add the following content

#!/bin/sh
iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -t mangle -F
iptables -t mangle -X
iptables -P INPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -P OUTPUT ACCEPT

Finally, run flush.iptables script with the following command

# sh flush.iptables

After running flush.iptables script, if you restart the iptables, you’ll see all the default rules again. So, flush is only temporary.

Permanently remove all the default firewall rules

Step 1. Flush all these rules temporarily, as we discussed above.
Step 2. Saving firewall rules to /etc/sysconfig/iptables. Type the following command

# /etc/init.d/iptables save

Or

# iptables-save > /etc/sysconfig/iptables

The post How To Flush/Remove All Iptables Rules In Linux appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.

Iptables should be installed by default on all CentOS 3.x, 4.x and 5.x installations. You can check to see if iptables is installed on your system by:

# rpm -q iptables

Sample output

iptables-1.3.5-5.3.el5_4.1

How to enable firewall

Login as root and type the following command

# /etc/init.d/iptables start
# chkconfig iptables on

If you are using IPv6, enter:

# /etc/init.d/ip6tables start
# chkconfig ip6tables on

And to see if iptables is actually running, we can check that the iptables modules are loaded, type the following command

# lsmod | grep ip_tables

Something look like:

ip_tables              29288  1 iptable_filter
x_tables               29192  6 ip6t_REJECT,ip6_tables,ipt_REJECT,xt_state,xt_tcpudp,ip_tables

How to disable firewall

Login as root and type the following command

# /etc/init.d/iptables stop
# chkconfig iptables off

If you are using IPv6, enter:

# /etc/init.d/ip6tables stop
# chkconfig ip6tables off

The post How To Enable/Disable Firewall On Centos / RedHat / Fedora appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.

chkconfig provides a  simple  command-line  tool  for  maintaining  the/etc/rc[0-6].d  directory  hierarchy by relieving system administrators of the task of directly manipulating the  numerous  symbolic  links  in those directories.

chkconfig has five distinct functions: adding new services for  management,  removing  services  from management, listing the current startup information for services, changing the  start-up  information  for  services, and checking the start-up state of a particular service.

Synopsis

chkconfig --list [name]
chkconfig --add name
chkconfig --del name
chkconfig [--level levels] name <on|off|reset>
chkconfig [--level levels] name

Example

List status for all services

chkconfig --list

List status for test service

chkconfig --list test

Add service called test

chkconfig --add test

Delete service called test

chkconfig --del test

Turn on & Turn off service

chkconfig --level 3 5 httpd off

The command above will turn off httpd service in run levels 3 and 5.

The post chkconfig Command appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.